Many current processors have multiple cores that operate at a common voltage and frequency domain. The peak current draw that the processor can actually consume is a function of the workload running on each core and the number of active cores. Depending on the number of active cores, the peak frequency at which the processor can run changes. The fewer the number of active cores, the higher the frequency at which the processor can run. Workloads that turn on and off cores (or utilize varying numbers of cores) at a high rate can cause the processor to change frequency at that rate.
When a processor performs a frequency transition to accommodate frequency changes, energy efficiency and performance can be impacted, as such transitions incur an idle down time penalty. Suitable mechanisms to avoid this penalty do not presently exist.